This article was based on Anil Seth’s TED Talk, “Your Brain Hallucinates Your Conscious Reality”:
|Your brain hallucinates your conscious reality | Anil Seth|
Anil Seth begins his talk about our conscious reality by describing his experience awakening from anesthesia. When he awoke, he felt no sense of the amount of time that elapsed while he was unconscious. This gap in consciousness is one of the great mysteries of science and philosophy.
This brings about the questions, what is consciousness and how does it happen? In theory it is the combined activity of billions of neurons in our brains that generate a conscious experience. This is what defines what you are experiencing in the here and now. Consciousness, as Seth describes it, is all there is for us and without it, there is no world, there is no self, leaving us with nothing. His research has found that consciousness has less to do with pure intelligence and more to do with our nature as living and breathing organisms.
Understanding consciousness is developing in a way similar to our understanding of biology. As biologists have learned more about living systems, they can explain them in detailed terms of physics and chemistry. With our increased understanding of metabolism, reproduction, and homeostasis, some of the basic mysteries of life have been solved. Similarly, with consciousness, once we start explaining its properties in terms of our brains and bodies, part of the mystery fades away.
Two Types of Consciousness
Consciousness can be thought of in two different ways. There are sensory experiences of the world around us that include things such as sights, sounds, and smells. Then there is the conscious self, which is a specific experience of being.
Your brain is trying to interpret the world based on streams of electrical impulses which are only indirectly related to things in the world. Its interpretation of the world is based on a process of informed guesswork. The brain combines the sensory signals it receives with its prior expectations or beliefs about the way the world is in order to identify what caused those signals. The brain does not actually hear sound or see light; it simply perceives what it believes is out there in the world.
Here is an example of how our brain perceives the world based on its prior knowledge. In the image below, the squares labeled A and B look like two different shades of grey. In reality, they are the exact same shade as you can see from the image on the right where the two patches are joined with a grey-coloured bar. The reason the brain sees the image on the left as two different colours is because it is using its prior expectations. These are built deeply into the circuits of the visual cortex, telling the brain that a cast shadow dims the appearance of a surface so that we see B as lighter than it really is.
Instead of perception depending on signals coming into the brain from the outside world, it depends more on perceptual predictions flowing in the opposite direction. We do not just passively perceive the world; we actively generate it. The world we experience comes as much, if not more, from the inside out as from the outside in.
Experiencing the Self
This understanding of perception can change how we experience the self. Seth describes our vision of our self as a controlled hallucination generated by the brain. There are many different ways to experience the self, from our body to our memories and our social interactions. Experiments have shown that these different ways of seeing our self are a fragile construct of the brain, where the brain makes its best guess about what is and what is not part of its body.
We also experience our bodies from within as internal sensory signals send messages to the brain about the state of our internal organs. This kind of perception is called interoception. It is critically important because perception and regulation of the internal state of the body work to keep us alive. Our most basic experiences of being a self are deeply grounded in the biological mechanisms that keep us alive. From here, we can start to see that our conscious experiences stem from this basic drive to stay alive. We experience the world and ourselves with, through, and because of our living bodies.
Implications of Perception
There are three implications of our brain’s perception of the world:
- Just as we can misperceive the world, we can misperceive ourselves when the mechanisms of prediction go wrong. This understanding opens opportunities in psychiatry and neurology for understanding conditions like depression and schizophrenia.
- Our sense of self cannot be reproduced by technology. We are biological, living animals whose conscious experiences are shaped by the biological mechanisms that keep us alive.
- Our conscious is just one possible way of being conscious. Our individual self and worlds are unique, but they are all grounded in biological mechanisms shared with other living creatures.
Nothing to Fear
Understanding our sense of self through our consciousness is a testament to the fact that we are not at the centre of the universe. This deeper understanding opens up a sense of wonder and a realisation that we are a part of a greater reality that shows us there is nothing to fear at the end of consciousness.